This invention relates to the processing of television signals and in particular to the reduction of interference between two frequency-modulated signals. The invention is primarily intended for use in the reduction of interference between two carrier signals which are modulated in frequency in accordance with a video signal and an audio signal respectively and which necessarily occupy partially overlapping ranges of frequencies because they must be accommodated within a limited bandwidth. The process of frequency modulation produces many sideband components and it is not in general possible to avoid interference between the sidebands of the frequency modulated signals merely by reducing the bandwidth of, for example, the modulating video signal. The invention is particularly intended for use in recording in video signal and an audio signal on the same track of a video disc.
The state of the art is illustrated by U.S. Pat. No. 3,830,968 which discloses the increase of the amplitude of an audio carrier when it is disturbed by sideband components of the video carrier. Such an increase is often excessive and can aggravate the mutual interference of the sidebands.